1. Technical Field of the Invention
The present invention relates to an electro-optical device and an electronic apparatus, and more specifically, to a structure of a transflective electro-optical device in which a plurality of pixel regions is arranged and each pixel region is provided with a light transmitting portion and a light reflecting portion.
2. Background Art
Transmissive liquid crystal display devices, reflective liquid crystal display devices and transflective liquid crystal display devices have been conventionally used as liquid crystal display devices used in various electronic apparatuses. Among these devices, transflective liquid crystal devices are configured such that when a backlight is turned on, a transmissive display is visible, and when the backlight is turned off or the circumference is very bright, a reflective display is visible. Accordingly, it is advantageous in that an optimum display can be implemented from the surroundings and that a power consumption of the backlight can be reduced. For these reasons, transflective liquid crystal display devices are widely used in portable electronic apparatuses, such as cellular phones or personal digital assistants.
It is known that a transflective liquid crystal display device comprises a reflective layer which has an aperture portion for every pixel region. Herein, for every pixel region, the aperture portion becomes a light transmitting portion and the remaining portion (other than the aperture portion), where the reflective layer is formed, becomes a light reflecting portion. Many of the light transmitting portions have one or two island shapes formed for every pixel region. An aperture ratio of the light transmitting portion in each pixel region is set in consideration of a balance between the transmissive display and the reflective display. Herein, a liquid crystal display device comprising color filters is provided with colored layers providing different color tones at adjacent pixel regions, and the aperture ratios of the light transmitting portions are adjusted in accordance with the color tones of the colored layers. Accordingly, the areas of the light transmitting portions in the adjacent pixel regions, each having a colored layer of a different color tone, are different from each other.
For example, FIG. 6 shows a pixel arrangement of a liquid crystal display device having color filters which are arranged in a stripe shape, that is, R, G and B pixels being sequentially arranged in a diagrammatically horizontal direction. Herein, in each pixel region, one aperture portion is formed at its central part to form the light transmitting portion, and the light reflecting portions are arranged at both vertical sides of the light transmitting portion. Each pixel region of R, G and B, which are arranged in the diagrammatically horizontal direction, has a light transmitting portion with an area different from each other. Further, the light reflecting portion is provided with a color filter aperture (a part in which the colored layer is not formed) having a suitable size. The color filter aperture is intended to adjust the saturation or luminosity of the reflective display.
However, in a conventional liquid crystal display device, since the areas of the light transmitting portions in the adjacent pixel regions as described above are different from each other, blurring of contours is generated in various displays and clearness in display quality is generally lacking. For example, as shown in FIG. 6, each pixel region may be rectangular which is long in a diagrammatically vertical direction and short in a diagrammatically horizontal direction. In this case, when the area of the aperture portion is adjusted, there is enough space that the length in the diagrammatically vertical direction may be changed. For this reason, the lengths of the aperture portion in the diagrammatically vertical direction are configured, to be different from each other between the adjacent pixel regions in the diagrammatically horizontal direction. Accordingly, between the adjacent pixel regions in the diagrammatically horizontal direction, the upper edge positions and lower edge positions of the light transmitting portions are configured to have an uneven shape due to a step difference in a diagrammatically vertical direction according to the difference of the areas of the light transmitting portions. Hence, if an outer edge of a display format extending in the diagrammatically horizontal direction is constituted, a contour line of the outer edge has an uneven shape due to the step difference of the upper and lower edge portions of the light transmitting portions. As a result, there is a problem in that the blurring of the display contours may result.
Further, various problems are also presented in different circumstances. For example, as shown in FIG. 6(A), when a black character is displayed against a white background for the transmissive display, a pair of minute black lines (which is constituted by the light reflecting portion of a pixel of white display) extending especially from an end portion of a black line toward a diagrammatically horizontal direction may be visible. The pair of minute black lines also extends in a zigzag shape according to the size of the light transmitting portion, so that it is likely to come into view. This results in an increase of the blurring of the display contours. In comparison, when a white character is displayed against a black background, a white line is more finely visible than a black line, and the size of the white line extending in a horizontal direction changes into an uneven shape. For this reason, a slight blurring of the display contours may be generated.
Further, as shown in FIG. 6(B), when a black character is displayed against a white background in the reflective display, the light transmitting portion of the white display is visible and extends in an uneven shape and consecutively in a minute black line shape at the end portion of the black line, so that the blurring of the display contours is highlighted. Further, when a white character is displayed against a black background, the blurring of the contours is weak, but a white line is visible and disconnected.
As described above, in the conventional electro-optical device, the blurring of the display contours is generated by forming the light transmitting portion and the light reflecting portion in every pixel region. In particular, since the edge portions of the light transmitting portions are provided at different positions between the adjacent pixel regions, there is a problem in that the blurring of the display contours is highlighted.
Hence, the present invention is designed to solve these problems, and it is an object of the present invention to reduce the blurring of the display contours caused by the light transmitting portion provided in every pixel region, and to improve the display quality of both the transmissive display and the reflective display in a transflective electro-optical device having a light transmitting portion and a light reflecting portion formed in every pixel region.